1. Field of the Invention
The present invention relates to an optical system unit and a projector including the optical system unit.
2. Description of the Related Art
Currently, a data projector is used in many cases to project an image displayed on a screen of a personal computer, an image of a video signal and, furthermore, an image by image data stored on a memory card on to a screen.
In many cases, this data projector employs a small, highly luminescent light source such as a metal halide lamp or an extra-high pressure mercury vapor lamp and is configured such that light emitted from the light source is split into three, red, green and blue, primary color components so as to be shone on to a display device referred to as a liquid crystal or DMD (Digital Micro Device) by a light source side optical system, and light transmitted through or reflected on the display device is projected on to a screen via a group of lenses which is referred to as a projection side optical system having a zooming function.
When projecting light from the light source unit, the DMD projects the light by controlling micromirrors in such a manner that light shone on to the micromirrors are reflected thereby towards the projection side optical system as light in an “on” state, while when not projecting light from the light source unit, the DMD controls the micromirrors in such a manner that light shone on to the micromirrors are reflected thereby towards positions where the light is not incident on the projection side optical system as light in an “off” state.
Then, due to the “off” state light being absorbed within an interior of the projector so as not to be incident on the projection side optical system, heat is generated in a portion where the light is so absorbed, and therefore, a space is provided where the heat so generated is dissipated.
In addition, in the projector employing the DMD, part of the “off” state light is incident on the projection side optical system as stray light, whereby a problem of deterioration of a projected image or reduction in luminescence has been caused by the stray light.
To cope with this, the Japanese Unexamined Patent Publication No. 2004-258439 proposes an invention which prevents the incidence and transmission of the stray light on and through the projection side optical system by disposing a light absorbing plate which disturbs the propagation of light which would make up stray light on an illumination side optical system.
In a conventional projector, however, since a light absorbing position to which “off” state light is shone on is heated to a high temperature, a cooling mechanism for the position to which the “off” state light is shone on becomes complex in construction, this making it difficult to make the projector small in size or thin in thickness.
In addition, the optical system unit needs to be formed by employing a highly heat-resistant metal in the position to which the “off” state light is shone on, and this has constituted a barrier when attempting to form components therefor by employing resin.
The invention has been made in view of the problems inherent in the related art that have been described above, and an object thereof is to provided an optical system unit which can be formed by employing resin or the like and which has a high cooling efficiency and a small projector which includes the optical system unit.